Ophthalmic Device and Tomographic Image Generation Device

This application is a continuation application of International Application No. PCT/JP2020/020945, filed May 27, 2020, the disclosure of which is incorporated herein by reference in its entirety. Further, this application claims priority from Japanese Patent Application No. 2019-102476, filed May 31, 2019, the disclosure of which is incorporated herein by reference in its entirety.

The present invention relates to an ophthalmic device and a tomographic image generation device.

In a known configuration of an optical coherence tomography device for acquiring a tomographic image of a posterior eye portion such as an ocular fundus of an examined eye, a lens attachment is disposed between an objective lens and the examined eye, and a tomographic image of an anterior eye portion such as the cornea or the like is acquired (United States Patent Application Laid-Open No. 2008/106696). By employing a lens attachment in such an optical coherence tomography device, tomographic images can be acquired for both a posterior eye portion and an anterior eye portion of an examined eye using a single device.

In the conventional optical coherence tomography device mentioned above, the lens attachment is disposed between the examined eye and the objective lens, and so alignment between a subject of examination and the imaging device needs to be re-adjusted every time a switch is made from posterior eye portion observation to anterior eye portion observation.

An ophthalmic device of a first aspect of the technology disclosed herein comprises a scanning member for scanning light that has been emitted from a light source; an objective lens comprising a first lens group and a second lens group in order from the scanning member side, the second lens group being a lens group having a positive power; and an optical element that is capable of being inserted into and removed from an optical path between the second lens group of the objective lens and the scanning member, wherein: in a case in which the optical element is not inserted into the optical path, the objective lens configures a first observation optical system, and light that is scanned by the scanning member is focused in a first region of an examined eye, and in a case in which the optical element has been inserted into the optical path, the objective lens and the optical element configure a second observation optical system, and light that is scanned by the scanning member is focused in a second region that is different from the first region of the examined eye.

An optical tomographic image generation device of a second aspect of the technology disclosed herein, comprises a light source that generates light for optical coherence tomography (OCT); a dividing section that divides light from the light source into measurement light and reference light; a scanning member for scanning the measurement light; an objective lens comprising a first lens group and a second lens group in order from a scanning member side, the second lens group being a lens group having a positive power; an optical element that is capable of being inserted into and removed from an optical path between the second lens group of the objective lens and the scanning member; an interference light detector that detects interference light obtained by synthesis of return light from an examined eye and the reference light; and an image generation section that generates a tomographic image of the examined eye based on the interference light detected by the detector, wherein: in a case in which the optical element is not inserted into the optical path, the objective lens configures a first observation optical system, and light that is scanned by the scanning member is focused in a first region of the examined eye, and in a case in which the optical element has been inserted into the optical path, the objective lens and the optical element configure a second observation optical system, and light that is scanned by the scanning member is focused in a second region of the examined eye.

Detailed description follows regarding exemplary embodiments of the present invention, with reference to the drawings.

Description follows regarding an ophthalmic deviceaccording to a first exemplary embodiment of the present invention, with reference to the drawings.illustrates a schematic configuration of the ophthalmic device.

For ease of explanation, scanning laser ophthalmoscope is referred to as SLO and optical coherence tomography is referred to as OCT.

In cases in which the ophthalmic deviceis installed on a horizontal plane with a horizontal direction taken as an X direction, a direction perpendicular to the horizontal plane is denoted as being a Y direction, and an optical axis direction of an image capture optical systemA is denoted as being a Z direction. The device is disposed with respect to an examined eye such that the center of the pupil of the examined eye is positioned on the optical axis in the Z direction. The X direction, the Y direction, and the Z direction are thus mutually perpendicular directions.

The ophthalmic deviceincludes an imaging deviceand a control device. The imaging deviceis provided with an SLO unitfor acquiring an image of an ocular fundusA of an examined eye, and with an OCT unitfor acquiring a tomographic image of the examined eye. Ocular fundus images generated based on SLO data acquired by the SLO unitare referred to hereafter as SLO images. Moreover, tomographic images generated based on OCT data acquired by the OCT unitare referred to hereafter as OCT images. Note that the SLO images are also sometimes referred to as two-dimensional ocular fundus images. More over, the OCT images are also sometimes referred to as ocular fundus tomographic images or anterior eye portion tomographic images, depending on the imaging site on the examined eye.

The ophthalmic deviceis an example of an “optical tomographic image generation device” of the technology disclosed herein.

The control deviceincludes a computer provided with a Central Processing Unit (CPU)A, Random Access Memory (RAM)B, Read-Only Memory (ROM)C, and an input/output (I/O) portD.

The control deviceis provided with an input/display deviceE coupled to the CPUA through the I/O portD. The input/display deviceE includes a graphical user interface to display images of the examined eyeand to receive various instructions from a user. The input/display deviceE may employ a touch panel display.

The control deviceis provided with an image processing devicecoupled to the I/O portD. The image processing devicegenerates images of the examined eyebased on data acquired by the imaging device.

The image processing deviceis an example of a “generation section” of technology disclosed herein.

Although the control deviceof the ophthalmic deviceis provided with the input/display deviceE as illustrated inand described above, the technology disclosed herein is not limited thereto. For example, a configuration may adopted in which the control deviceof the ophthalmic deviceis not provided with the input/display deviceE, and instead a separate input/display device that is physically independent of the ophthalmic deviceis provided. In such cases, the display device is provided with an image processing processor unit that operates under the control of the CPUA in the control device. Such an image processing processor unit may display SLO images and the like based on an image signal output as an instruction by the CPUA.

The imaging deviceoperates under the control of the control device. The imaging deviceincludes the SLO unit, an image capture optical systemA, and the OCT unit. The image capture optical systemA is moved in the X, Y, Z directions by an image capture optical system drive sectionM under control by the CPUA. Alignment (positional alignment) between the imaging deviceand the examined eyemay be performed, for example, not only by moving the imaging devicealone, but also by moving the entire ophthalmic devicein the X, Y, Z directions.

An SLO system is implemented by the control device, the SLO unit, and the image capture optical systemA illustrated in.

The SLO unitinclude plural light sources. For example, as illustrated in, the SLO unitinclude a B-light (blue light) source, a G-light (green light) source, an R-light (red light) source, an IR-light (infrared light (for example near infrared light)) source. Light emitted from each of the light sources,,,is directed onto a single optical path by respective optical members,,,,. The optical members,are configured by mirrors, and the optical members,,are configured by beam splitters. B-light is guided through the optical members,,and onto the optical path of the image capture optical systemA. G-light is guided through the optical members,and onto the optical path of the image capture optical systemA. R-light is guided through the optical members,and onto the optical path of the image capture optical systemA. IR-light is guided through the optical members,and onto the optical path of the image capture optical systemA. Note that LED light sources and laser light sources may be employed as the light sources,,,. Note that the following description is of an example in which laser light sources are employed therefor. Total reflection mirrors may be employed as the optical members,. Moreover, dichroic mirrors, half-mirrors, or the like may be employed as the optical members,,.

The light sources,,,are examples of “laser light sources” of technology disclosed herein.

The SLO unitis configured so as to be capable of switching between various light emission modes such as a light emission mode in which G-light, R-light, B-light, and IR-light are separately emitted, a light emission mode in which all of these lights are emitted at the same time or a number of these lights are emitted at the same time, and the like. Although the example illustrated inincludes four light sources, i.e. the B-light (blue light) light source, the G-light light source, the R-light light source, and the IR-light light source, the technology disclosed herein is not limited thereto. For example, the SLO unitmay further include a white-light light source. In such cases a light emission mode in which white light is emitted alone, or the like, may also be set in addition to the various light emission modes listed above.

Laser light introduced into the image capture optical systemA from the SLO unitis scanned in the X direction and the Y direction by scanning sections (,), described later. The scanned light passes through the pupiland is irradiated onto a posterior eye portion (for example, an ocular fundusA) of the examined eye. Reflected light that has been reflected by the ocular fundusA is introduced into the SLO unitthrough the image capture optical systemA.

The scanning sections (,) are examples of “scanning members” of technology disclosed herein.

The reflected light that has been reflected at the ocular fundusA is detected by light detection elements,,,provided in the SLO unit. In the present exemplary embodiment the SLO unitincludes the B-light detection element, the G-light detection element, the R-light detection element, and the IR-light detection elementcorresponding to the plural light sources, namely, the B-light source, the G-light source, the R-light source, and the IR-light source. The B-light detection elementdetects B-light reflected at the beam splitter. The G-light detection elementdetects G-light that has passed through the beam splitterand been reflected at the beam splitter. The R-light detection elementdetects R-light that has passed through the beam splitters,and been reflected at the beam splitter. The IR-light detection elementdetects IR-light that has passed through the beam splitters,,and been reflected at the beam splitter. Avalanche photodiodes (APD) may, for example, be employed as the light detection elements,,,.

The light detection elements,,,are examples of “laser light detectors” of the technology disclosed herein.

Under control of the CPUA, the image processing devicegenerates SLO images corresponding to each color using signals respectively detected by the B-light detection element, the G-light detection element, the R-light detection element, and the IR-light detection element. The SLO images corresponding to each color include a B-SLO image generated using a signal detected by the B-light detection element, a G-SLO image generated using a signal detected by the G-light detection element, an R-SLO image generated using a signal detected by the R-light detection element, and an IR-SLO image generated using a signal detected by the IR-light detection element. Moreover, when in a light emission mode in which the B-light source, the G-light source, and the R-light sourceemit light at the same time, an RGB-SLO image may be synthesized from the R-SLO image, the G-SLO image, and the B-SLO image generated using the respective signals detected by the R-light detection element, the G-light detection element, and the B-light detection element. Moreover, when in a light emission mode in which the G-light sourceand the R-light sourceemit light at the same time, an RG-SLO image may be synthesized from the R-SLO image and the G-SLO image generated using the respective signals detected by the R-light detection elementand the G-light detection element. Although in the first exemplary embodiment an RG-SLO image is employed as the SLO image, there is no limitation thereto, and another SLO image may be employed.

Dichroic mirrors, half-mirrors, or the like may be employed as the beam splitters,,,.

An OCT system is a three-dimensional image acquisition device realized by the control device, the OCT unit, and the image capture optical systemA illustrated in. The OCT unitincludes a light sourceA, a sensor (detection element)B, a first optical couplerC, a reference light optical systemD, a collimator lensE, and a second optical couplerF.

The first optical couplerC is an example of a “dividing section” of technology disclosed herein. The sensor (detection element)B is an example of an “interference light detector” of technology disclosed herein.

The light sourceA generates light for optical coherence tomography. A super luminescent diode (SLD) or the like may, for example, be employed as the light sourceA. The light sourceA emits light of low coherence from a broad band light source having wide spectral width. The light emitted from the light sourceA is divided at the first optical couplerC. After one division of the divided light has been made into parallel light by the collimator lensE, to serve as measurement light, the parallel light is introduced into the image capture optical systemA. The measurement light is scanned in the X direction and the Y direction by scanning sections (,), described later. The scanned light is irradiated onto the posterior eye portion through the anterior eye portion of the examined eye and the pupil. Measurement light that has been reflected at the anterior eye portion or the posterior eye portion passes through the image capture optical systemA and is introduced into the OCT unit. The measurement light then passes through the collimator lensE and the first optical couplerC before being incident to the second optical couplerF. Note that although in the present exemplary embodiment an example is given of SD-OCT employing an SLD as the light sourceA, technology disclosed herein is not limited thereto, and SS-OCT employing a wavelength s wept light source instead of the SLD may be adopted.

The other division of the light emitted from the light sourceA and divided by the first optical couplerC is introduced as reference light into the reference light optical systemD, and is made incident to the second optical couplerF through the reference light optical systemD.

The measurement light (return light) reflected and scattered by the examined eyeis combined with the reference light by the second optical couplerF to generate interference light. The interference light is detected by the sensorB. The image processing devicegenerates a tomographic image of the examined eyebased on a detection signal (OCT data) from the sensorB.

In the first exemplary embodiment the OCT system generates a tomographic image of an anterior eye portion or a posterior eye portion of the examined eye.

The anterior eye portion of the examined eyeis a section serving as an anterior eye segment including, for example, the cornea, the iris, the angle, the lens, the ciliary body, and a portion of the vitreous body. The posterior eye portion of the examined eyeis a section serving as a posterior eye segment including, for example, the remaining portion of the vitreous body, the retina, the choroid, and the sclera. Note that the anterior eye portion of the vitreous body is a section in the vitreous body at the cornea side of a boundary of an X-Y plane passing through a nearest point of the lens to the eyeball center, and the posterior eye portion of the vitreous body is a section in the vitreous body that is not the vitreous body of the anterior eye portion.

The OCT system generates, for example, a tomographic image of the cornea when the anterior eye portion of the examined eyeis the imaging target site. Moreover, the OCT system generates, for example, a tomographic image of the retina when the posterior eye portion of the examined eyeis the imaging target site.

The posterior eye portion and the anterior eye portion are respective examples of a “first region” and a “second region” of the technology disclosed herein.

illustrates a schematic configuration diagram of the image capture optical systemA. The image capture optical systemA includes an objective lens, a beam splitter, a horizontal scanning section, a relay lens device, a beam splitter, vertical scanning sections,, a focus adjustment device, and a collimator lens, disposed in order from the examined eyeside.

Dichroic mirrors, half-mirrors, or the like may, for example, be employed as the beam splitters,.

The horizontal scanning sectionis an optical scanner for horizontal-direction scanning of SLO scanning laser light or of OCT measurement light introduced through the relay lens device. In the present exemplary embodiment the horizontal scanning sectionemployed is common to both an SLO optical system and an OCT optical system, however, there is no limitation thereto. A horizontal scanning section may be respectively provided in each of the SLO optical system and the OCT optical system.

The collimator lenstakes light that was emitted from the OCT unit, propagated through a fiber and emitted from the fiber endas the measurement light, and makes this parallel light.

The focus adjustment deviceincludes plural lenses,. The focus position of the measurement light in the examined eyeis adjusted by appropriately moving the plural lenses,respectively along the optical axis direction according to the imaging site in the examined eye. Note that although not illustrated in the drawings, in cases in which a focus detection device is provided, the lenses,may be driven by a focus adjustment device according to a state of focus detection, so as to implement an autofocus device that performs focusing automatically.

The vertical scanning sectionis an optical scanner for vertical-direction scanning the measurement light introduced through the focus adjustment device.

The vertical scanning sectionis an optical scanner for vertical-direction scanning the laser light introduced from the SLO unit.

The relay lens deviceincludes the plural positive power lenses,. The relay lens deviceis configured by the plural lenses,such that positions of the vertical scanning sections,are conjugate to a position of the horizontal scanning section. More specifically, the relay lens deviceis configured such that positions of the center of the scanning angles of both scanning sections are conjugate to each other.

The beam splitteris disposed between the relay lens deviceand the vertical scanning section. The beam splitteris an optical member that combines the SLO optical system and the OCT optical system. The beam splitterreflects the SLO light emitted from the SLO unittoward the relay lens device, and transmits the measurement light emitted from the OCT unittoward the relay lens device. The measurement light emitted from the OCT unitis two-dimensionally scanned by the vertical scanning sectionand the horizontal scanning section. The light emitted from the SLO unitis two-dimensionally scanned by the vertical scanning sectionconfiguring the SLO optical system and the horizontal scanning section. The two-dimensionally scanned OCT measurement light and the two-dimensionally scanned SLO laser light are respectively introduced into the examined eyethrough the objective lensconfiguring a common optical system. The SLO laser light reflected at the examined eyeis introduced into the SLO unitvia the objective lens, the horizontal scanning section, the relay lens device, the beam splitter, and the vertical scanning section. The OCT measurement light that has passed through the examined eyeis introduced into the OCT unitvia the objective lens, the horizontal scanning section, the relay lens device, the beam splitter, the vertical scanning section, the focus adjustment device, and the collimator lens.

Examples of sections appropriately employed as the horizontal scanning sectionand the vertical scanning sections,include resonant scanners, galvanometer mirrors, polygon mirrors, rotating mirrors, Dove prisms, double Dove prisms, rotation prisms, MEMS mirror scanners, acousto-optical elements (AOM), and the like. In the present exemplary embodiment a galvanometer mirror is employed as the vertical scanning section, and a polygon mirror is employed as the vertical scanning sections. Note that in cases in which a two-dimensional optical scanner such as a MEMS mirror scanner or the like is employed instead of an optical scanner such as a polygon mirror, a galvanometer mirror, or the like, the relay lens devicemay be omitted due to being able to perform angle scanning of the incident light in two-dimensions using the reflection elements therein.

The objective lensincludes a first lens groupand a second lens group, in order from the horizontal scanning sectionside. At least the second lens groupis a positive lens group having a positive power overall. In the first exemplary embodiment the first lens groupis also a positive lens group having a positive power overall. The first lens groupand the second lens groupeach include at least one positive lens. In cases in which the first lens groupand the second lens groupeach include plural lenses, a negative lens may be included in each of the first lens groupor the second lens groupas long as each of these lens groups has a positive power overall.

The first lens groupand the second lens groupconfiguring the objective lensare separated from each other by a maximum air distance between lens planes of the objective lens along the optical axis. Note that there may be a glass sheet of no power present at a position between the first lens groupand the second lens group. Such a glass sheet is not considered as being a lens belonging to either the first lens groupor the second lens group, and the first lens groupand the second lens groupare separated from each other by the maximum air distance.

The image capture optical systemA includes an anterior eye portion observation-use optical moduleas an optical module that can be inserted into and removed from the optical path of the objective lens, and a sensorS to detect the inserted/removed state of the optical module. As will be described in detail later, in the first exemplary embodiment, in cases in which the optical moduleis not disposed on the optical path of the objective lens, a posterior eye portion observation optical system(see also) is configured as an observation optical system, and the ophthalmic deviceacquires an image of the posterior eye portion of the examined eyetherewith. However, in cases in which the optical modulehas been inserted into the optical path of the objective lens, an anterior eye portion observation optical system(see also) is configured as the observation optical system, and the ophthalmic deviceacquires an image of the anterior eye portion of the examined eyetherewith. As described in detail later, in the first exemplary embodiment, the optical moduleis inserted into and removed from the optical path of the observation optical system either manually by an operator (for example, an ophthalmologist) or automatically. The optical moduleis inserted into the optical path between the first lens groupand the second lens group, or is removed from the optical path by movement along non-illustrated rails or by rotational movement of a non-illustrated turret. The sensorOS for detecting the inserted/removed state of the anterior eye portion observation-use optical modulemay be a sensor that detects either that the optical modulehas been inserted into the image capture optical system or that the optical modulehas been removed therefrom, or may be a sensor that detects both states.